Various instruments are available or proposed for measuring magnetic field intensity. A degree of complexity is introduced into many of such devices because of the difficulty of quantitatively measuring magnetic field directly. For example, it is possible to use a magnetostrictive material to respond to the intensity of the magnetic field, and to associate that magnetostrictive material with a further system for measuring magnetostrictively induced dimension changes to produce a quantitative measure of field intensity.
It is not seen that the art has progressed to the stage of providing a magnetometer which concurrently meets the requirements of: (a) simplicity of design and ruggedness of construction requiring little attention to fine recalibration, (b) miniaturization and portability of the entire measuring system, and (c) an adequate degree of sensitivity across an adequately wide range of measurable field intensities.
For example, with respect to simplicity and ruggedness, many magnetometers are still of the laboratory instrument variety, and even when used in the field require substantial care in setup and operation. With respect to miniaturization or portability, the magnetic sensors themselves can be made quite small, but they usually require substantial ancillary components such as electronic power supplies and other complex circuit modules in order to complete a functional system. With respect to sensitivity and range, accurate readings can be made at particular ranges, but known systems are not adequately capable of meeting a wide range of field intensity measurements with the same degree of desirable accuracy.
A potential field of applications not satisfied by currently available magnetometers is the personal magnetic field intensity monitor. Such a device can be considered as similar to a radiation monitor worn by those dealing with radioactive material. However, the magnetometer device would monitor magnetic field exposure and provide an output measure of field intensity to which the wearer has been exposed. Because of the relative complexity of known magnetometer systems, it has not heretofore been possible to configure a small sized (say pocket calculator size) device which could be carried by the user to perform such a function.